I had this problem, too, because I overlooked something vital. Go to your settings and put this entire link in the "Subscriptions" box: iros://Url/http$pastebin.com/raw.php?i=dDBkYkDu
After that, try to Check Subs again / use the "Search" button in the Catalog tab.
That's the link it uses to draw the mod list and info from the server.